In a physical vapor deposition (PVD) chamber, uniform distribution of process gases within a closed process chamber is desired during the deposition process. Certain reactive processes such as TiN or TaN benefit when gas is directly injected into the process chamber to ensure uniform film properties such as resistance (Rs) and thickness uniformity. However, a typical PVD chamber indirectly introduces gas into the process chamber through multiple shields (e.g. upper and lower shield).
In addition, traditional PVD chambers measure the pressure outside the process cavity between the shield and chamber body. However, due to gas flow dynamics, this pressure is not representative of actual pressure inside the process cavity. Dynamics further change when gases are delivered into the process chamber. Thus, difficulty arises in determining the actual process pressure a wafer and target is subjected to.
Accordingly, the inventors have provided a system and apparatus for uniform gas injection and improved pressure measurement.